Phase-failure protection



July 26, 1927. 1,637,043

B. w. JONES 1 was FAILURE raprucrrok Filed Aug. 28., 1925 Fig.2.

Inventor:

, Benjamin W. Jones.

H is AtCorn ey.

Patented July 26, 1927. p

1 UNITED STATES:

1,637,043 PATENT OFFICE.)

BENJAMIN W. JONES, OF SGH ENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PHASE-FAILURE PROTECTION.

' Application filed August 28, 1925. Serial No. 53,176.

My invention relates to protective devices for polyphase circuits which will automatically open the circuit upon a reversal of the phases and in response to a failure of a por- 5 tion of the phases and keep the circuit open until polyphase energization of the circuit is restored. i

The invention is particularly applicable to the control of polyphase motors, although the invention is not necessarily limited thereto. In a prior patent of mine, No. 1,620,556, dated March 8, 1927, I have disclosed and broadly claimed a phase failure, phase reversal protective device having series windings and. a circuit controlling member which is operated by the windings in one direction 'upon normal phase energization of the circuit and operated in the opposite direction by the windings upon less than normal phase 0 energization of the windings. In another Patent No. 1,620,555, dated March 8, 1927,

in which I am a joint patentee with Nobel A.

Wolfe, We have disclosed and claimed the specific form of the device which has gone into extensive use.

The device of the said applications, while entirely operative for the ordinary conditions encountered, leaves something to be desired for certain special conditions, among which is that of the automatic protection of a motor located at an isolated or somewhat inaccessible place. Since the protective de" vice has series windings, it will be completely deenergized when the motor controlled thereby is disconnected from the polyphase supply circuit-upon the failure of a portion of the phases. A feature of the device is that normally closed contacts may be employed and this type of contacts has numerous advantages for this class of service, but a disadvantage is nevertheless introduced thereby in the remote automatic control of a translating device in that when the controlled circuit is opened by the device, the less than normal phase energization of the device is discontinued and the contacts thus return to the closedposition. This affects the automatic-reclosing of the controlled circuit and then the immediate re-opening 50 thereof. This telegraph action is obviously undesirable, and the object of the.

present invention is to prevent this action.

In carrying the invention into'efiect in the form which I now regard as the preferred form, I provide a shunt winding type pro- -form in Fig. 1 and in Fig. 2 the constructectivedevice which cooperates with the said series Winding type of device, the shunt deyice being constructed and arranged with its contacts in series relation with thecon-v tacts of the series type of device so that upon the failureof a portion of the phases the opening of the controlled circuit will be effected and the shunt type device will thereupon prevent the reclosing of the circuit until normal phase energization ofthe circuit is restored. The shunt type device iseunsatisfactory for the complete and sole control of the protected circuit since if the failure of a portion of the phases occurs in the supply circuit, the device will receive polyphase energization from the motor and if the failure occurs in the motor the device will receive polyphase energization from the supply circuit. With the combinationof the series and shunt Winding type devices of the present invention, this difficulty 'is avoided.

Fora better understanding of the invention, reference is had to the accompanying drawings, in which Fig. l is a very simplified diagram of a motor control system having reverse phase and phase failure protection 'in accordance with the inventionand Fig. 2

is a detail showingthe reverse phase, phase failure protective device of the said Jones and {(olfe Patent No. 1,620,555, dated March 1 a, 92 p i i The electric motor 10 is arranged to be connected to thethree phase alternating current'supply, circuit 11 by means of thecone taotor 12. This contactor is controlled by the reverse phase, phase failure protective device13 which has series: windings in less than all of the phases. This protective device is indicated in very diagrammatical 95 tion details thereof are more fully shown. The protective device 13 has normally closed contacts, the movable contact 14 being under the control of the, non-magnetic metallic disc 15 of the protective device 13. The contactor 12 is also under the joint control of the protective device. or relay 16. This relay. has shunt windings, as indicated, and normally open contacts, the movable contact 17 thereof being arranged to be operated by the plunger 18 of the device. In general it may 'be said that with-polyphase energizution of the supply circuit 11, the shunt windings of the relay 16 will set up a magnetiopull on the plunger 18 in such a direction thatthe plunger will be lifted and the contact 17 be rought in engagement with the correspond-' ing stationary contacts so that the winding of the contactor 12 will be energized to operate the contactor and connect the motor 10 to the supply circuit. In case there should be a phase failure, either in the supply circuit 11. between the cont-actor 12 and the motor or in the motor itself, the disc 15 of the series protective relay 13 will operate the movable contact 14 to (leenergize the line contact-or 12. causing this contactor to open and disconnect the motor from the supply circuit. In case the phase failure occurs in the supply circuit 11 leading to the motor 10, the shunt type protective device 16 will also promptly operate and the contact 17 will drop, thereby cooperating with the relay 13 in effecting the openin of the line contactor 12. The opening of t e line contactor will prevent the relay 16 from receiving polyphase ener ization from the motor so that even thougi the movable contact 14 of the relay 13 is permitted to automatically reclose in response to the opening of the line contactor 12, nevertheless this contactor will not be reenergized until polyphase energization of the supply circuit is restored. This is due to the fact that the relay 16 requires polyphase energization to pick up and close its controlled contacts.

In Fig. 2 I have disclosed merely a detail of the essential elements of the reverse phase, phase failure protective relay of the said Jones and \Volfe application. This relay comprises a metallic disc 15 0f non-magnetic material such as copper or the like. This disc is under the control of the magnetic field set up by the windings 19 and 20 which are connected in series relation with one of the conductors of the supply circuit, and the windings 21 and 22 which are connected in series relation with another of the conductors of the polyphase supply circuit. Each of the windings of this relay is disposed on a core of magnetic material and these cores are symmetrically disposed about the axis on which disc 15 rotates. The adjustable controlling member 23 cooperates with the disc 15, the cores on which the winding of the relay are disposed and the relay windings in such a way that there aretwo torques set up in the disc 15, one is a single phase or tooth torque and the other is a torque set up by the rotatin magnetic field produced by the windings o the relay. The single phase torque of the device is independent of polyphase energization and therefore persists after the failure of a ortion of the phases of the circuit to which the windings of the device are connected. The polyphase torque normally predominates to effect a clockwise rotation of the disc 15 and keep the rojection 24 of the disc in engagement wit the stop 25 mounted in the adjustable controlling member 28. The single phase or tooth torque is nevertheless present ut is overcome by the polyphase torque. \Vhen a portion of the phases of the circuit is opened, as for example the o ning of a phase such as would deencrgizet e windings 19 and 20, the single phase torque set up by the windings 21 and 22 will effect a counterclockwise rotation of the disc 15 and bring the projection 24 into engagement with the relay switch contact member 14 and thus open the normally closed contacts of the relay. The windings 19 and 20 of the relay are energized from the secondary of the current transformer 26 and the windings 21 and 22 'are energized from the secondary of the current transformer 27. The relation between the single phase and the polyphase torques of the relay may be adjusted by adjusting the position of the member 23 with reference to the cores on which the windings of the device are disposed. The windings and the cores on which these windings are mounted are preferably mounted on a stationary support and the adjustable controlling member 23 is mounted for a limited rotation on the shaft 28 on which the disc 15 is mounted for rotation. In practice, when the member 23 is adjusted to the desired position with reference to the cores of the electroma ets this member will be left in that position throughout the normal operation of the device.

v The rela 16 is provided with shunt windings as in 'cated, each winding being connected to one of the separate oontactors in the supply circuit 11 and the other ends of the windings bein connected together at a common point. e relay windings are interconnected in such a manner that with the phase rotation in the proper direction the resultant magnetic ull acts on the plunger 18 in the u ward rection and the contact 17 is move to the closed position. When the phase rotation is reversed, theresultant pull on the plunger 18 is asplied in the o posite direction, and ass' by gravity, e plunger falls and the contacts open. This relay cannot be relied upon to operate its contacts in case of an open phase when the motor is running and remains connected to the supply circuit because of the fact that the counter polyphase potential is generated by the rotor of the motor while this rotor is in motion.

As thus constructed and arranged, and with the various parts in their respective positions as indicated, in Fig. 1, the operation of my invention is as follows: Assume that the disconnectin switch 29 in the supply circuit '11 is closed and the disconnecting switch 30 in the winding circuit of the line "contactor 12 and the disconnecting switch 31 in the circuit of the windings of the rela 16 are also closed. In case normal polyp 8st energization of the supply circuit 11 is presratus shown is only illustrative and that ent, the windin of at e line contactor 12 the invention can be carried out by other will be energize from the su ply circuit 11 means. a through the contacts of the re ay 13 and the What I claim as new and desire to secure contacts of the relay 16. This will efiect the by Letters Patent of the United States is closing of'the line contactor l2 and connect 1. Phase failure protective means for the motor 10 to the supply circuit. In case polyphase circuits, the said means compristhere should be a failure of a portion of the mg two cooperating parts, one of said parts phases either, in the supply circuit 11, the having series windings and mechanism conductors between the supply circuit and under the control thereofarrangedto effect the contacts of the contactor 12, the con- 'the opening of theconnection withthe cirductors between the contactor 12 and the cuit u on less than normal phase excitation motor 10 orin the windings of the motor itof said windings, andthe "other of said parts self, by reason of the fact that the relay 13 having windings connected in'shunt relation is provided with series windings, this relay with said circuit which control the closing will operate at all events and the projection of the connection with the circuit when nor- 24 of the disc 15 will be brought into enmal phase energization of the 'circuit is relgagement with the switch member 14, therestored. i i

y opening the energizing circuit of the line 2. In combination, a device for protecting contactor 12. If the open phase occurs in a polyphase circuit upon;the failure ofa porthe supply circuit this relay 16 will receive tion of the phases, the said device havin a poly hase energization from the motor 10 pluralit of series windings and a mem er unti the motor is disconhected from the operate by at least a portion of the windsupply circuit so that the openin of the ings to effect the opening of the connection contactor 12 not only deenergizes t e motor with said circuit upon less than normal but also renders the relay 16 res onsive to phase excitation of said windings, and a secthe phase failure condition of t e supply 0nd controlling device having windings concircuit 11 so that this relay will then open nected in shunt relation with said circuit after the opening of the line contactor 12. which prevents the closing of the connection By reason of the fact that the relay 16 has with said circuit after the failure of a porshunt windings, this relay will not reclose its tion ofthe hases until normal phase ener- 1 contacts to automatically deenergize the line gization of t e circuit is restored. contactor 12 until polyphase energization of 3. In combination, a. device for opening a the supply circuit has been restored. The polyphase circuit upon the failure of a porrelay 13, however, will automatically reclose tion of the phases, the said device having 1 its contacts as soon as the line contactor 12 controlling switch contact mechanism, a pluopens, because of the fact that this relay has ralityof series windings and a member operseries windings. The motor is thus autoated by at least a portion of said windings matically protected from being reconnected to open said switch mechanism upon less to the supply circuit-until the proper conthan normal phase excitation of said wind- I06 ditions have been brought about, namely ings, and a second controlling device having until a- 1y hase energization of the supply switch contact mechanism in series relation circuit liiis n restored. with the switch contact mechanism of said In casethe phase failure occurs eithe in first device, the said second device havm the motor or between the motor and the line windings connected in shunt relation wit I10 contactor 12, the relay 13 will automatically said circuit and being arranged to prevent operate to deenergize the line contactor 12 the closing oftfthe connection with said cirand disconnect the motorfrom the supply cuit after the failure of a portion of the circuit. When this condition occurs, the unphases untiljrnormal phase energization of desirable telegraphing action previously re- ,the circuit-is restored. ferred to will to e place. However, the oc- J A. In combination, an open phase roteccurrences of phase failure either in the tin device having windings connecte to be motor or in the connections between the cir energized inseries relation with the trans cuit interrupting device for the motor are ]at' device protected thereby, the sold d eextremely rare and a. tele raphing' action of .vio e 'fiaving contacts which are normally 1n the motor disconnectinggevlce under these one position when said windings are deconditions is not of a serious practical ob- ,energized and when there is normal phase jection because of the rare ocurronee of such energization thereof and which are operated conditions. to a second position by said windings upon In accordance with the of'the phase failure, a line contactor in the supply 1" patentstatutes, I have-described theprincircuit which is deenergized and ope ciple of operation of my invention, that under the control of sax device u on the with theapparatus which I now oonsi er to occurrence of phase failure and w ich in represent the best embodiment thereof, bnt opening deenergizes the windin .of saig I desire to have it understood that the appadevioe, a second protective evice hav- 3 ing windings connected in shunt relation with the supply circuit for preventing the automatic rec osure of said contactor when said contacts of said first mentioned protective device return until normal phase energization of the circuit is-restored. p

5. In combination, a line contactor'fori a polyphase circuit, a protective device for eflecting the o ening of said contactor upon the opening of one or more of the phases of said circuit, the said device having series windings and normally closed controlling contacts operated to the open position by said windings upon less than normal phase excitation thereof, a second protective device for said contactor, the said second protective device havin shunt windings and contacts controlled t iereby to move to the open position upon the failure of aportion of the phases of said circuit, and connections throu h which the said devices jointly control sai contactor to efiect the opening of the same upon the occurrence of less than normal phase energization and keep the same open until the polyphase energization of said circuit is restored.

to their biased position nee-mes 6. In combination, a polyphaae supply circuit, an alternating current motor, a normally open contactor included between said supply circuit and said motor, the said contactor having a winding which closes and maintains said contactor closed when the winding is energized, a phase failure and phase reversal ClIClllhCOlltlOlllfl protective relay having series windin s an connected between said contactor an said motor, the said relay having normally closed contacts for controlling said contactor winding and mechanism under the control of said windings which efiect the openin of said contacts u normal p ase excitation of sa' windings and upon the occurrence of phase reversal, and a second relay havin windings connected in shunt relation wit said source and havin normally open contacts for preventing t e automatic reenergization of said contactor winding and the automatic reclosure of said contactor until normal phase energization of said circuit is restored.

In witness whereof I have hereunto set my hand this 27th day of August 1925.

BENJAMIN w. JONES. 

